Square Kilometre Array

The SKA will be the biggest radio telescope ever built, with a collecting area two orders of magnitude larger than the current technology. This will be achieved by creating a large array of antenna stations and dispersing them over an area up to 3000 km, with half of the stations being within a 5 km radius. Not only will the sensitivity of the SKA revolutionise discoveries made with radio astronomy, its huge span of antenna also ensures an angular resolution that will be able to detect faint emissions from galaxies much farther away than current technology allows.

A computer model of how the HI universe has evolved. (Steve Furlanetto et al 2003, MNRAS)

This high angular resolution will also help achieve one of five key objectives drawn up by the radio astronomy community, titled “Cradle of Life”. This involves looking inside the dust rings of young stars to determine how other earth-like planets form, and being able to detect any sources of radio transmissions could confirm intelligent life in the universe.

The second project titled “Probing the Cosmic Dawn and Epoch of Reionisation” analyses radio emission from early Universe neutral hydrogen to explore the birth and growth of structure in the Universe. The SKA has the sensitivity to reach the Cosmic Dawn, the period in the first billion years when the first stars and galaxies began to illuminate the Universe for the first time. It will also explore the Epoch of Reionisation, when these first galaxies and stars transformed the Universe to the rich and structured cosmos we observe today. This also ties in closely with the fifth project, focussing on the evolution of the stars and galaxies. This can be seen in the figure below which demonstrates a current model of how the Universe has evolved.

Also, by being able resolve much more detail of the galaxies, monitoring magnetic fields can lead to answering many fundamental questions of magnetism in general, such as determining if the overall Universe is magnetic. This ability ties into the third major goal, “The Origin and Evolution of Cosmic Magnetism”, whereby studies of the Faraday rotation of cosmic signals could help determine the abundance of magnetism amongst the stars.

As the name suggests, the fourth project, “Strong Field Tests of Gravity Using Pulsars and Black Holes” deals with observations of Pulsars and Black holes. By having the increased sensitivity of the SKA, radio astronomers will be able to find Pulsars neighbouring black holes, and use precise timing of the spins to help test Einstein’s general relativity theory with much stronger fields. This excellent timing resolution will also be able to accurately measure millisecond pulsars leading to the detection of passing gravity waves.

The final key project for the SKA is “Galaxy evolution, cosmology and dark energy”, involving the detection of 21cm HI emissions of many more galaxies in much more detail. By mapping these detections to their redshift (from the observed wavelengths), radio astronomers will also be able to map out the universe with much more accuracy and develop a pattern for clustering of galaxies.

Although each of these projects are the main driving force behind the construction of the Square Kilometre Array, a device of such high sensitivity and resolution is set to make many discoveries in all fields of astronomy. This natural step in radio astronomy technology, however, is long overdue, as the collecting area of optical telescopes are constantly being upgraded with little been done with those designed to measure radio frequencies.

This large advancement in technology raises many questions regarding new antenna for the SKA, with many institutions around the world putting forward design concepts.

The SKA will be hosted by Australia and South Africa, building on the substantial investment in infrastructure and expertise that already exists in both locations. The International Centre for Radio Astronomy Research (ICRAR), a joint venture between Curtin University and The University of Western Australia, will be directly involved with the components of the SKA located at the Murchison Widefield Array (MWA) in Australia’s Midwest.